Ammonia Hydrate Research Articles

Synergistic Pyridinic N/Pyrrolic N configurations in rGO/CNT composite sulfur hosts for high-performance lithium-sulfur batteries

Significant progress has been made in the field of nitrogen-doped carbon sulfur host materials to address the shuttle effect, expansion effect, and conductivity issues of lithium-sulfur (Li-S) battery cathode materials. However, there has been limited study on the synergistic effects of different nitrogen configurations. In this work, ammonia and hydrazine hydrate were used as nitrogen source precursors to prepare three kinds of rGO and CNT composite sulfur hosts with different nitrogen configurations. Ammonia is conducive to the formation of Pyrrolic N, while hydrazine hydrate is conducive to the formation of Pyridinic N. Lithium-sulfur batteries assembled with 3NG/CNT/S which has similar Pyridinic N and Pyrrolic N contents, have a specific initial discharge capacity of 1345 mAh/g at 0.2 C. The initial discharge specific capacity at 2 C was 819 mAh/g, and after 400 cycles, the remaining capacity is 667 mAh/g. The synergistic impact mechanism of Pyridinic N/Pyrrolic N configurations was further revealed by first principles calculations. The results indicate that Pyridinic N/Pyrrolic N configurations enhance electronic non-locality, significantly improve the reactivity of carbon materials, reduce the Gibbs free energy during polysulfide reactions, and accelerate the reaction rate.

Effect of Copper Inclusion in Zinc sulfide Thin Films for Photocatalytic Applications

Transparent and well-adhered pure zinc sulfide (ZnS) and different concentrations of copper-doped zinc sulfide thin films were obtained on glass substrates by the Chemical bath deposition process. Zinc acetate, copper acetate and thiourea were employed as sources of Zn2+, Cu2+ and S2- ions, respectively; ammonia and hydrazine hydrate served as complexing agents for the preparation of pure zinc sulfide and different concentrations of copper-doped zinc sulfide thin films. By adjusting the ammonia concentration, the prepared solution pH was maintained at 11. The prepared samples were deposited at the rates of 60 and 90 minutes each, with the bath temperature being held at 80 °C. The structural, morphological and optical properties of the prepared films were characterized by XRD, FE-SEM and EDX, and the results were reported. The XRD patterns revealed that all thin films possess a polycrystalline cubic zinc blended structure and that the prepared pure and copper-doped ZnS thin films have good crystallinity; the crystallite sizes were less than 20 nm. From the FE-SEM spectra, it is understood that the pure and Cu-doped ZnS thin films were uniformly coated with spherical morphology. The surface morphology, optical characteristics and deposition mechanism were all obviously impacted by the ammonia concentration. Additionally, under UV light irradiation, the effect of the photocatalytic property of the prepared thin films with methylene blue dye was studied and the corresponding dye degradation graphs were reported.

Equation of state of ammonia dihydrate up to 112 GPa by static and dynamic compression experiments in diamond anvil cells

Understanding the high-pressure behavior of ammonia hydrates is relevant for modeling the interior of solar and extrasolar icy bodies. We present here the results of high-pressure x-ray diffraction studies on ammonia-dihydrate (ADH) at room temperature (298 K) up to 112 GPa, employing both static and dynamic compression experiments performed in diamond anvil cells. The derived pressure-volume (P-V) compression curves are in excellent agreement regardless of the compression technique. In contrast to early theoretical predictions, our results indicate the stability of the disordered molecular alloy (DMA) phase, a body centered cubic (bcc) structure, and the absence of self-ionization in the investigated pressure range. By combining the P-V data from seven different compression runs, we derive the first equation of state for ADH-DMA based on the third-order Birch-Murnaghan formalism with best-fit parameters: ${V}_{0}=23.96\ifmmode\pm\else\textpm\fi{}0.03$ (${\AA{}}^{3}$/molecule), ${B}_{0}=9.95\ifmmode\pm\else\textpm\fi{}0.14$ GPa, and ${B}_{0}^{\ensuremath{'}}=6.59\ifmmode\pm\else\textpm\fi{}0.03$. The instantaneous bulk modulus directly derived from the quasicontinuous compression curves displays a smooth increase upon compression that further supports the absence of structural transitions.

Observation of a Plastic Crystal in Water-Ammonia Mixtures under High Pressure and Temperature.

Solid mixtures of ammonia and water, the so-called ammonia hydrates, are thought to be major components of solar and extra-solar icy planets. We present here a thorough characterization of the recently reported high pressure (P)-temperature (T) phase VII of ammonia monohydrate (AMH) using Raman spectroscopy, X-ray diffraction, and quasi-elastic neutron scattering (QENS) experiments in the ranges 4-10 GPa, 450-600 K. Our results show that AMH-VII exhibits common structural features with the disordered ionico-molecular alloy (DIMA) phase, stable above 7.5 GPa at 300 K: both present a substitutional disorder of water and ammonia over the sites of a body-centered cubic lattice and are partially ionic. The two phases however markedly differ in their hydrogen dynamics, and QENS measurements show that AMH-VII is characterized by free molecular rotations around the lattice positions which are quenched in the DIMA phase. AMH-VII is thus a peculiar crystalline solid in that it combines three types of disorder: substitutional, compositional, and rotational.

Comparison of Life Cycle Environmental Impact between Two Processes for Silver Separation from Copper Anode Slime.

The cost of silver separation is lowered when ammonia and hydrazine hydrate are replaced with sodium thiosulfate and sodium dithionite in the process of extracting of metallic silver from copper anode slime. The overall environmental impact of two types of copper silver separation processes from anode slime has been analyzed\\using the LCA method. Through the subdivision analysis, we found the raw materials or emission items that should be improved first. The following conclusions are drawn: (1) The life cycle environmental impact of the sodium thiosulfate process is much lower than the existing process; (2) The resource and environmental impacts of the sodium thiosulfate method are mainly in the fields of climate change, photochemical smog, and ionizing radiation, exceeding two-thirds of the impact on all of the resources and environment; (3) In terms of input and output items, the main impact of the new process on the resources and the environment is concentrated on the use of sodium hydroxide, accounting for 33.98% of the total equivalent, followed by sodium thiosulfate and sodium carbonate, respectively. These input–output items are the key fields that need attention in future technology improvement.

Ammonia Mono Hydrate IV: An Attempted Structure Solution

The mixed homonuclear and heteronuclear hydrogen bonds in ammonia hydrates have been of interest for several decades. In this manuscript, a neutron powder diffraction study is presented to investigate the structure of ammonia monohydrate IV at 170 K at an elevated pressure of 3–5 GPa. The most plausible structure that accounts for all features in the experimental pattern was found in the P21/c space group and has the lattice parameters a=5.487(3) Å, b=19.068(4) Å, c=5.989(3) Å, and β=99.537(16) deg. While the data quality limits discussion to a proton-ordered structure, the structure presented here sheds light on an important part of the ammonia–water phase diagram.

Why We Are all Using a Nonexistent Substance: NH₄OH.

Ammonium hydroxide does not exist, but it is commercially available, although everybody knows that it should be called 'ammonia hydrate' . The reason is not scientific. It is purely commercial and will be explained in the text.

Dimethyl carbonate production via transesterification reaction using nitrogen functionalized graphene oxide nanosheets

Nitrogen-functionalized graphene oxide (GO) nanocatalysts were prepared using ammonia, methylamine, ethylamine, and hydrazine hydrate as a nitrogen source. Nanocatalysts samples were thoroughly characterized using XRD, Raman, FTIR, XPS, FESEM, TEM, and TGA techniques. Quantitative and qualitative analyses of surface acidic and basic sites were done by NH3- and CO2-TPD techniques. Nanocatalysts were further examined for DMC production via transesterification reaction of propylene carbonate (PC) with CH3OH. Quantitative analysis of nitrogen-containing functional groups in the prepared sample with respect to other functional moieties was performed. Among various nanocatalysts, ammonia functionalized GO (AGO) was found to be the best for DMC production. At optimized reaction conditions of temperature (180 °C), time (6 h), and catalyst dose (1 wt% with respect PC), the highest DMC yield of ∼50% was observed. Reusability studies using AGO nanocatalyst were conducted up to four consecutive test cycles to evaluate catalysts' potentiality towards DMC synthesis. Thus, N-functionalized GO is a useful metal-free nanocatalyst that could also be explored for other chemical processes.

Formation Conditions of Titan’s and Enceladus’s Building Blocks in Saturn’s Circumplanetary Disk

Abstract The building blocks of Titan and Enceladus are believed to have formed in a late-stage circumplanetary disk (CPD) around Saturn. Evaluating the evolution of the abundances of volatile species in this disk as a function of the migration, growth, and evaporation of icy grains is then of primary importance to assess the origin of the material that eventually formed these two moons. Here we use a simple prescription of Saturn’s CPD in which the location of the centrifugal radius is varied, to investigate the time evolution of the icelines of water ice, ammonia hydrate, methane clathrate, carbon monoxide, and dinitrogen pure condensates. To match their compositional data, the building blocks of both moons would have had to form in a region of the CPD situated between the icelines of carbon monoxide and dinitrogen at their outer limit, and the iceline of methane clathrate as their inner limit. We find that a source of dust at the location of centrifugal radius does not guarantee the replenishment of the disk in the volatiles assumed to be primordial in Titan and Enceladus. Only simulations assuming a centrifugal radius in the range 66–100 Saturnian radii allow for the formation and growth of solids with compositions consistent with those measured in Enceladus and Titan. The species are then able to evolve in solid forms in the system for longer periods of time, even reaching an equilibrium, thus favoring the formation of Titan and Enceladus’s building blocks in this region of the disk.

Production of Nanofiber Materials Based on Macromolecular Hyaluronic Acid by Electrospinning

Hyaluronic acid-based nanofiber scaffolds imitating the natural extracellular matrix, which is promising for use in tissue engineering, have been prepared by electrospinning. Hyaluronic acid is part of many organs and tissues; it is a biologically active component capable of being involved in cell proliferation and migration. The high viscosity of solutions of the macromolecular biopolymer significantly complicates the preparation of nanofiber scaffolds based on it. Rheological studies have made it possible to determine the solvent composition that contributes to a decrease in the viscosity of the spinning solution. The highest Newtonian viscosity of a 1% hyaluronic acid solution in water is 25 Pa s; in the case of using a mixture of ammonia hydrate (10%) and dimethylformamide at a ratio of 2 : 1, this parameter decreases to 1.147 Pa s. The use of a special spinning cell with a small-diameter nozzle and a high pressure (up to 10 atm) has provided the formation of hyaluronic acid-based nanofibers with a diameter of 100–300 nm.

Acylation of indolyl subsituted β-ketonitriles. The way to new indolo[2,3-c]pyrilium and β-carboline derivatives

Aim. To synthesize 4-cyanoindolo[2,3-c]pyrilium salts and examine their reactivity towards N-nucleophiles.Results and discussion. The acylation reaction of 2-(indolyl-3)-2-aroylacetonitriles under acid catalysis conditions was studied. 4-Cyanoindolo[2,3-c]pyrillium borofluorides were obtained, and ketonitrile enolacylates were isolated as by-products of the reaction. Treatment of the 4-cyanoindolo[2,3-c]pyrilium salts with ammonia led to 4-cyano-β-carbolines while the interaction of the salts with hydrazine hydrate resulted in formation of pyrazolo[3’,4’:5,6]pyrido[3,4‑b]indoles – derivatives of a new heterocyclic system. The latter are formed via recyclization involving the pyran ring and the cyano group.Experimental part. Upon the treatment of 2-(indolyl-3)-2-aroylacetonitriles with acetic anhydride/tetrafluoroboric acid mixture, the acylation of the indole fragment in position 2 was followed by cyclization, resulting in formation of 4-сyanoindolo[2,3-c]pyrilium salts. The reactivity of the pyrylium salts was studied on the examples of their interaction with N-nucleophiles – ammonia and hydrazine hydrate. The structure of the compounds synthesized was confirmed by 1H NMR, IR spectroscopy and elemental analysis.Conclusions. It has been found that moderate yields of 4-сyanoindolo[2,3-c]pyrilium salts are the result of competing acylation of the hydroxyl group of enol ketonitrile, which blocks the pyran ring formation. Recylization of the salts with ammonia leads to 4-cyano-β-carbolines. Transformation of the pyran ring with hydrazine hydrate proceeds with the participation of the cyano group as a tandem reaction with formation of pyrazolo[3’,4’:5,6]pyrido[3,4-b]indoles.Received: 22.06.2020 Revised: 03.10.2020 Accepted: 23.10.2020

The comparative analysis of the mineral nitrogen fertilizers

According to the results of physical and chemical modeling, the chemical form of nitrogen fertilizers has a significant effect on the thermodynamic parameters of systems with their application. The chemical activity of nitrogen in sandy soils is higher than in clay soils, and decreases in the series: potassium nitrate - ammonium nitrate - urea - ammonia hydrate, i.e., decreases with the transition from the oxidized form of nitrogen +5 to reduced -3. Potassium and sodium nitrate are optimal with regard to the chemical activity of nitrogen in sandy soils. In clay soils, on the contrary, the maximum activity of nitrogen is provided by the use of urea containing a reduced form of nitrogen. The reactivity of oxygen is higher in clay soils and increases with the transition from oxidized to reduced forms of nitrogen. Therefore, to increase the activity of oxygen in sandy and clay soils, it is preferable to use urea and ammonia water. The binding efficiency of atmospheric nitrogen increases in the series: ammonia hydrate, urea - ammonium nitrate - potassium nitrate, and thus, systems containing highly oxidized nitrogen are favorable for fixing atmospheric nitrogen.

Quantify the effect of temperature on the electrical resistivity, yield stress, and HPHT fluid loss of the bentonite-clay drilling mud modified with acrylamide polymer

In this study, the effect of acrylamide polymer modified bentonite on the fluid loss and yield stress of water-based drilling mud at different temperatures up 85 °C were studied. Bentonite content in the drilling mud was varied from 2 to 8% by the weight of water. The polymer content was varied between 0 and 0.24% by the weight of bentonite. The bentonite and polymer were characterized using X-ray analysis and thermal gravimetric analysis (TGA). Based on the X-ray diffraction analyses the major constituents of the bentonite were montmorillonite (MMT), (Na, Ca)0.33(Al, Mg)2(Si4O10)(OH)2·nH2O), feldspar (Albite) (NaAlSi3O8), kaolinite (Al2Si2O5(OH4)), Beidellite (Na, Ca0.5)0.3Al((Si, Al)4O10)(OH)2·nH2O and quartz (SiO2), also it was shown the major constituents of acrylamide polymer were ammonium hydroxide carbonate amine ((NH4)·CH3CONH2) and ammonia hydrate (2NH3H2O). The results showed that the polymer-modified bentonite decreased the fluid loss of the drilling mud by 28–52% based on the bentonite content and temperature in drilling mud. TGA analyses showed a notable reduction in the weight of bentonite between 600 and 800 °C. Modifying the bentonite using 0.24% of polymer reduced the total weight loss at 800 °C from 6.42 to 1.26%. an 80% reduction. The polymer modification decreased the yield stress (τo) of drilling mud by 30–60% based on the bentonite content and temperature. The results showed that fluid loss decreased with an increasing amount of polymer. The electrical resistivity of the drilling mud decreased from 8.5 to 3.9 Ω-m, a 53% reduction when the bentonite content increased from 2 to 8% at room temperature. The electrical resistivity of the filter cake formation of the bentonite drilling mud modified with 0.24% polymer decreased by 33–57% based on the bentonite content and temperature. The polymer is an excellent potential additive for reducing the fluid loss and yield stress of drilling muds. The effects of bentonite and polymer content on the model parameters have been quantified using a nonlinear model (NLM). The NLM quantified the effect of polymer treatment on all the model parameters.

Cryovolcanic flooding in Viking Terra on Pluto

A prominent fossa trough (Uncama Fossa) and adjacent 28-km diameter impact crater (Hardie) in Pluto's Viking Terra, as seen in the high-resolution images from the New Horizons spacecraft, show morphological evidence of in-filling with a material of uniform texture and red-brown color. A linear fissure parallel to the trough may be the source of a fountaining event yielding a cryoclastic deposit having the same composition and color properties as is found in the trough and crater. Spectral maps of this region with the New Horizons LEISA instrument reveal the spectral signature of H2O ice in these structures and in distributed patches in the adjacent terrain in Viking Terra. A detailed statistical analysis of the spectral maps shows that the colored H2O ice filling material also carries the 2.2-μm signature of an ammoniated component that may be an ammonia hydrate (NH3·nH2O) or an ammoniated salt. This paper advances the view that the crater and fossa trough have been flooded by a cryolava debouched from Pluto's interior along fault lines in the trough and in the floor of the impact crater. The now frozen cryolava consisted of liquid H2O infused with the red-brown pigment presumed to be a tholin, and one or more ammoniated compounds. Although the abundances of the pigment and ammoniated compounds entrained in, or possibly covering, the H2O ice are unknown, the strong spectral bands of the H2O ice are clearly visible. In consideration of the factors in Pluto's space environment that are known to destroy ammonia and ammonia-water mixtures, the age of the exposure is of order ≤109 years. Ammoniated salts may be more robust, and laboratory investigations of these compounds are needed.

Plastic and superionic phases in ammonia–water mixtures at high pressures and temperatures

The interiors of giant icy planets depend on the properties of hot, dense mixtures of the molecular ices water, ammonia, and methane. Here, we discuss results from first-principles molecular dynamics simulations up to 500 GPa and 7000 K for four different ammonia–water mixtures that correspond to the stable stoichiometries found in solid ammonia hydrates. We show that all mixtures support the formation of plastic and superionic phases at elevated pressures and temperatures, before eventually melting into molecular or ionic liquids. All mixtures’ melting lines are found to be close to the isentropes of Uranus and Neptune. Through local structure analyses we trace and compare the evolution of chemical composition and longevity of chemical species across the thermally activated states. Under specific conditions we find that protons can be less mobile in the fluid state than in the (colder, solid) superionic regime.

High-pressure phase stability and elasticity of ammonia hydrate

Abstract Phase stability and elasticity of ammonia hydrate have been studied using Raman spectroscopy and Brillion scattering in diamond-anvil cells up to 53 GPa at 300 K. Here we have established the high-pressure phase diagram of ammonia hydrate in three different compositions, including ammonia monohydrate (AMH, NH3·H2O), dihydrate (ADH, NH3·2H2O), and trihydrate (ATH, NH3·3H2O). In contrast to previous experimental results, our Raman and Brillouin measurements at 300 K have shown that all three ammonia hydrates start to dehydrate at 2.1–2.2 GPa. Dehydration of the ammonia hydrate leads to the formation of single-crystal ice-VII and an increase in the concentration of NH3 in the residual liquid. The residual liquid finally turns into solid ammonia hemihydrate phase II (AHH-II) at 4–4.6 GPa, leading to a 28% jump in the compressional-wave velocity (VP). Considering a 10–15 vol% NH3 in the mantle of ice giants, AHH should thus be the dominant form of NH3 coexisting with H2O-ice in the ice giants. Further Brillouin measurements provide crucial constraints on the VP of AHH and the single-crystal elasticity of ice-VII at high pressures and 300 K. VP of AHH increases smoothly with pressure. No anomalous change in VP of AHH was identified up to 39 GPa, although a solid to solid phase transition was noted to occur at ~18 GPa by Raman measurements. In addition, the elasticity of single-crystal ice-VII, which was the dehydration product of ammonia hydrate, has been determined up to 53 GPa at 300 K. The deviation of C12 from C44 observed at 11.4 and 14.6 GPa could be caused by the hydrogen bond symmetrizations or the ordering of dipole of single-crystal ice-VII. An abnormal softening in the elastic moduli C11, C12, and the adiabatic moduli KS together with stiffening in C44 was observed between 42 and 53 GPa, which should be caused by the transition from ice-VII to its pre-transitional state. Of particular interest is the dramatic increase in the anisotropy of ice-VII with increasing pressure. Combining the sound velocity of AHH and ice-VII, we have modeled the VP of ice giants with a volume ratio of 20% AHH and 80% ice-VII in the mantle. The obtained high-pressure phase diagram and elastic properties of ammonia hydrate could contribute to understanding the structure of the mantle in the ice giants and satellites.

RESEARCHES OF NITROGEN-PHOSPHORUS SOLUTIONS

A pilot plant for producing nitrogen-phosphorus solutions is created. Polyphosphoric acid (85 %) and ammonia hydrate (25 %) are used as the original substance. The methodology of the experiment and reagents input sequence are developed, the analysis of the resulting solution composition is carried out. The effect of phosphoric acid concentration and temperature on the conversion coefficient P2O5of the interaction with ammonia hydrate is determined, the maximum value and rational set of parameters are determined.. The reactions that occur during the interaction of reagents are determined, the mechanism and composition of the solution, which includes NH4H2PO4, (NH4)2HPO4, (NH4)2H2P2O7, (NH4)3HP2O7, (NH4)4P2O7 and H2O, is defined. In the solid phase ~ 40 % of (NH4)2HPO4 and (NH4)3xPO4 x H2O are also formed as total amount. The following rational technological parameters of the interaction process are determined: temperature, 293– 308 K; reaction time –1–4 s, mixing intensity Re = 120–200; relation NH3 x H2O to H3PO4 – 40:60; 50:50; 60:40, concentration H3PO4 – 70–85 %.

Conformational 2-Fold Interpenetrated Uranyl Supramolecular Isomers Based on (6,3) Sheet Topology: Structure, Luminescence, and Ion Exchange

Six new 2-fold interpenetrated uranyl coordination polymers with two distinct types of (6,3)-net layers, (H3O)[(UO2)(L)]·H2O (1), (Hbipy)[(UO2)(L)]·H2O (2), (Hbib)[(UO2)(L)]·H2O (3), (H2dib)[(UO2)2(L)2]·H2O (4), [Zn(H2O)6][(UO2)2(L)2]·5H2O (5), and (NH4)[(UO2)(L)]·H2O (6), (bipy = 2,2'-bipyridine, bib = 4,4'-di(1 H-imidazol-1-yl)-1,1'-biphenyl, and dib = 1,4-di(1 H-imidazol-1-yl)benzene), were hydrothermally prepared from a tripodal polycarboxylate ligand, tri(4-carboxyphenyl)phenylsilane (H3L), with different N-bearing organic templates as the stacking templates and charge compensators. Structural analyses indicate that these compounds comprise two sets of conformational supramolecular isomers because of the same framework compositions but different conformations of the carboxylate ligands. The solid-state emission spectra of compounds 1-6 were recorded. Ion-exchange studies revealed that the ammonia hydrate in 6 can be selectively substituted by alkali metal cations with appropriate ionic radii, and that the resulting structures remain stable, as demonstrated by crystallographic characterization.

Investigation of Preparation, Solubility and Stability Properties of Nickel Hydrazine Nitrate (NiHN)

AbstractFollowing an initial, brief, review of the environmental problems associated with the use of lead based primers, and also some of their potential replacements, this study investigated the preparation of the promising, lead free, energetic material nickel hydrazine nitrate by different methods. All three methods trialed produced the same, analytically indistinguishable, compound but with minor changes in visual appearance. The solution properties governing the precipitation process were investigated in a controlled pH titration experiment. Product solubility in a number of common solvents was investigated. Aqueous ammonia and hydrazine hydrate proved the best “non‐destructive solvents” for the solid. UV spectroscopy and conductivity of the solutions obtained was used as an indicator of the processes involved in the solubility. Using the critical pH conditions for precipitation from aqueous solutions of hydrazine and nickel nitrate the formation constant for the tris hydrazine complex was determined. Also using the solubility of the tris‐hydrazine complex in concentrated hydrazine hydrate an equilibrium constant for the formation of the soluble hexa‐hydrazine complex from insoluble tris hydrazine complex was determined. These values were compared with similar values for nickel hydrazine complexes with other anions. The origins of these differences were discussed. Further work on controlling and measuring the particle size of the NiHN produced should be considered.

Trimetallic oxide nanocomposites of transition metals titanium and vanadium by sol-gel technique: synthesis, characterization and electronic properties

Novel titanium and vanadium based trimetallic oxide nanocomposites (TMONCs) have been synthesized using metal salts of titanium-vanadium along with three others metals viz. tin, aluminium and zinc as precursors by the sol-gel method. Aqueous ammonia and hydrazine hydrate were used as the reducing agents. The preparations of nanocomposites were monitored by observing the visual changes during each step of synthesis. The synthesized TMONCs were characterized using UV–vis, SEM, EDX, TEM and DLS. Band gap of the synthesized TMONCs ranges from 3–4.5 eV determined using tauc plot. FTIR study revealed the molecular stretching and bending peaks of corresponding M–O/M–O–M bonds thus confirming their formation. Molecular composition and particle size were determined using EDX and DLS respectively. Molecular shape, size and surface morphology have been examined by SEM and TEM.